1. Field of the Invention
The invention relates to a method for managing packet traffic in Internet applications, more particularly to a method and multi-queue packet scheduling system for managing network packet traffic with minimum performance guarantees and maximum service rate control.
2. Description of the Related Art
U.S. Pat. Nos. 6,072,772 and 6,317,416 disclose conventional packet scheduling systems that are capable of supporting different service classes. The different service classes differ primarily in their Quality of Service (QoS) requirements, such as throughput, delay, delay jitter and loss rate. The prior art has also recognized the importance of maintaining minimum performance guarantees for the different service classes. Many algorithms have been proposed heretofore to ensure minimum performance guarantees. See, for example, A. K. Parekh and R. G. Gallager, “A Generalized Processor Sharing Approach to Flow Control in Integrated Services Networks: The Single-Node Case”, IEEE/ACM Transactions on Networking, Vol. 1, No. 3, pp. 344–357, June 1993; J. C. R. Bennett and H. Zhang, “WF2Q: Worst-case Fair Weighted Fair Queueing”, Proc. IEEE INFOCOM '96; and others.
In WFQ and WF2Q, each service class is assigned with a reserved weight in bandwidth sharing of an output link. WFQ and WF2Q provide a minimum rate guarantee for each service class that is equal to the product of the link capacity and the quotient of the reserved weight of the service class divided by the total reserved weight of the service classes. The shared bandwidth rate of each service class is equal to the product of the link capacity and the quotient of the reserved weight of the service class divided by the total reserved weight of backlogged ones of the service classes.
However, while the known service disciplines provide minimum performance guarantees, they lack maximum service rate control. Without maximum service rate control, leased line customers may use more bandwidth than what they paid for. In other words, customers do not pay more for higher service rates, which is to the disadvantage of carriers and service providers. Moreover, without maximum service rate control, total outgoing traffic attributed to specific applications or organizations cannot be restricted to enforce management policies. In addition, for some service classes, such as video or audio service classes, extra requests for the sharing of bandwidth from other unbacklogged service classes are not admissible because the amount of shared bandwidth is not predictable. Furthermore, for some multimedia streaming applications, use of higher-than-designed bandwidth can overflow the receiving buffer such that the service quality is degraded. There is thus a need to ban excess bandwidth sharing for specific service classes and applications.